Photocatalytic degradation of eosin yellow and quinaldine red under visible light irradiation by magnetite nanoparticles

Abstract

Magnetite nanoparticles were prepared by co-precipitation at three different temperatures and used as photocatalysts for the degradation of eosin yellow (EY) and quinaldine red (QR) under visible light irradiation. Powder X-ray diffraction confirmed the cubic spinel crystalline structure of iron oxide (Fe₃O₄). HRTEM images showed Fe₃O₄ nanoparticles with mean particle sizes of 10.6–12.9 nm. The energy bandgaps of the magnetite nanoparticles obtained from Tauc plots are in the range 2.96–3.36 eV. The photocatalytic degradation of eosin yellow by the Fe₃O₄–1 nanoparticle shows a maximum efficiency of 89.8%, while Fe₃O₄–2 degraded 85.9% of quinaldine red after 180 min. Optimal photocatalytic degradation was obtained using 1.2 mg L⁻¹ with pH 4 being the best for eosin yellow and pH 9 is optimum for quinaldine red degradation. The photostability and reusability of the as-prepared magnetite nanoparticles were examined over four consecutive cycles, which indicate that the degradation efficiency was reduced by 0.11–17.06%. The good photoactivity and photostability under visible light make the system suitable for practical use in the wastewater treatment industries.